Kynurenine pathway abnormalities are state-specific but not diagnosis-specific in schizophrenia and bipolar disorder

Schizophrenia (SCZ) and bipolar disorder (BD) are associated with immunological dysfunctions that have been hypothesized to lead to clinical symptomatology in particular through kynurenine pathway abnormalities. The aim of this study was thus to investigate the impact of serum kynurenine metabolite levels on diagnosis, clinical state, symptom severity and clinical course in a large French transdiagnostic cohort of SCZ and BD patients. Four patient groups (total n = 507) were included in a cross-sectional observational study: 1) hospitalized acute bipolar patients (n = 205); 2) stable bipolar outpatients (n = 116); 3) hospitalized acute schizophrenia patients (n = 111) and 4) stable schizophrenia outpatients (n = 75), in addition to healthy controls (HC) (n = 185). The quantitative determination of serum kynurenine metabolites was performed using liquid chromatography-tandem mass spectrometry. Kynurenine levels were lower in all patients combined compared to HC while ANCOVA analyses did not reveal inter-diagnostic difference between SCZ and BD. Interestingly, hospitalized patients of both diagnostic groups combined displayed significantly lower kynurenine levels than stabilized outpatients. Psychotic symptoms were associated with lower quinaldic acid (F = 9.18, p=<.001), which is KAT-driven, whereas a longer duration of illness contributed to abnormalities in tryptophan (F = 5.41, p = .023), kynurenine (F = 16.93, p=<.001), xanthurenic acid (F = 9.34, p = .002), quinolinic acid (F = 9.18, p = .003) and picolinic acid (F = 4.15, p = .043), metabolized through the KMO-branch. These data confirm illness state rather than diagnosis to drive KP alterations in SCZ and BD. Lower levels of KP metabolites can thus be viewed as a transdiagnostic feature of SCZ and BD, independently associated with acute symptomatology and a longer duration of illness. Quinaldic acid has seldomly been investigated by previous studies and appears an important state marker in SCZ and BD. As serum samples are used in this study, it is not possible to extrapolate these findings to the brain.

Kynurenine-3-monooxygenase expression is activated in the pancreatic endocrine cells by diabetes and its blockade improves glucose-stimulated insulin secretion

Type 2 diabetes is associated with an inflammatory phenotype in the pancreatic islets. We previously demonstrated that proinflammatory cytokines potently activate the tryptophan/kynurenine pathway (TKP) in INS-1 cells and in normal rat islets. Here we examined: (1) the TKP enzymes expression in the diabetic GK islets; (2) the TKP enzymes expression profiles in the GK islets before and after the onset of diabetes; (3) The glucose-stimulated insulin secretion (GSIS) in vitro in GK islets after KMO knockdown using specific morpholino-oligonucleotides against KMO or KMO blockade using the specific inhibitor Ro618048; (4) The glucose tolerance and GSIS after acute in vivo exposure to Ro618048 in GK rats. We report a remarkable induction of the kmo gene in GK islets and in human islets exposed to proinflammatory conditions. It occurred prominently in beta cells. The increased expression and activity of KMO reflected an acquired adaptation. Both KMO knockdown and specific inhibitor Ro618048 enhanced GSIS in vitro in GK islets. Moreover, acute administration of Ro618048 in vivo improved glucose tolerance, GSIS and basal blood glucose levels in GK rats. These results demonstrate that targeting islet TKP is able to correct defective GSIS. KMO inhibition could represent a potential therapeutic strategy for type 2 diabetes.

20-Hydroxyecdysone activates the protective arm of the RAAS via the MAS receptor

20-Hydroxyecdysone (20E) is a steroid hormone that plays a key role in insect development through nuclear ecdysteroid receptors (EcR/RXR complex) and at least one membrane GPCR receptor (DopEcR). It also displays numerous pharmacological effects in mammals, where its mechanism of action is still debated, involving either an unidentified GPCR or the estrogen ERβ receptor. The goal of this study was to better understand 20E mechanism of action in mammals. A mouse myoblast cell line (C2C12) and the gene expression of myostatin (a negative regulator of muscle growth) were used as a reporter system of anabolic activity. Experiments using protein-bound 20E established the involvement of a membrane receptor. 20E-like effects were also observed with angiotensin(1-7), the endogenous ligand of MAS. Additionally, the effect on myostatin gene expression was abolished by Mas receptor knock-down using siRNA or pharmacological inhibitors. 17β-Estradiol (E2) also inhibited myostatin gene expression, but protein-bound E2 was inactive, and E2 activity was not abolished by angiotensin(1-7) antagonists. A mechanism involving cooperation between the MAS receptor and a membrane-bound palmitoylated estrogen receptor is proposed. The possibility to activate the MAS receptor with a safe steroid molecule is consistent with the pleiotropic pharmacological effects of ecdysteroids in mammals and, indeed, the proposed mechanism may explain the close similarity between the effects of angiotensin(1-7) and 20E. Our findings open up many possible therapeutic developments involving stimulation of the protective arm of the renin-angiotensin-aldosterone system (RAAS) with 20E.

[Elaboration and psychometric properties of a well-being scale at work. The Serenat study among employees in occupational medicine unit]

BACKGROUND

Well-being at work is nowadays a major public health challenge. It includes, among others, absence of psychological (anxio-depressive) symptoms, perceived positive work conditions (environment and organization), happiness and good quality of life at work. Many studies have shown that social support and control at work protect mental health while high job demands and effort-reward imbalance are risk factors for anxiety and depression. There is currently no global indicator to measure both the state of mental health and social working conditions. The main objective of this work is to construct and explore the psychometric properties of scale of well-being at work called "Serenat" in order to validate it.

METHODS

The Serenat Scale is a self-report questionnaire composed of 20 items. All items are scored on a four-point Likert scale ranging from 0 (strongly disagree) to 3 (strongly agree) resulting in a range of 0 to 60. It was constructed from data collected from the literature and from consultations in an Occupational Health Unit. From January 2014 to May 2017 193 subjects who have consulted an occupational doctor are included in this cross sectional survey. Validation included item quality and data structure diagnosis, internal consistency, intraobserver reliability evaluation and external consistency.

RESULTS

The Serenat scale showed very good item quality, with a maximal non-response rate of 0.01 % per item, and no floor effect. Factor analysis concluded that the scale can be considered unidimensional. Cronbach's alpha of internal consistency was 0.89. The intraclass correlation coefficient for intraobserver reliability was 0.89. Serenat scale was correlated with HADS (r=-0.54; P<0.001), STAI-Y (r=-0.78; P<0.001) and BDI-13 (r=-0.57; P<0.001).

CONCLUSION

Serenat's well-being at work scale shows good psychometric properties for final validation. It could be useful to occupational physicians for individual and collective screening.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02905071.

Identification of a novel 2-oxindole fluorinated derivative as in vivo antitumor agent for prostate cancer acting via AMPK activation

The key metabolic sensor adenosine monophosphate-dependent kinase (AMPK) has emerged as a promising therapeutic target for cancer prevention and treatment. Besides its role in energy homeostasis, AMPK blocks cell cycle, regulates autophagy and suppresses the anabolic processes required for rapid cell growth. AMPK is especially relevant in prostate cancer in which activation of lipogenic pathways correlate with tumor progression and aggressiveness. This study reports the discovery of a new series of 2-oxindole derivatives whose AMPK modulatory ability, as well as the antitumoral profile in prostate cancer cells, was evaluated. One of the assayed compounds, compound 8c, notably activated AMPK in cultured PC-3, DU145 and LNCaP prostate cancer cells. Likewise, compound 8c caused PC-3, DU145 and LNCaP cells viability inhibition. Selective knocking down of α1 or α2 isoforms as well as in vitro assays using human recombinant α1β1γ1 or α2β1γ1 AMPK isoforms revealed that compound 8c exhibit preference for AMPKα1. Consistent with efficacy at the cellular level, compound 8c was potent in suppressing the growth of PC-3 xenograft tumors. In conclusion, our results show that a new 2-oxindole fluorinated derivative exerts potent in vivo antitumor actions against prostate cancer cells, indicating a promising clinical therapeutic strategy for the treatment of androgen-independent prostate cancer.

Expression of the kynurenine pathway enzymes in the pancreatic islet cells. Activation by cytokines and glucolipotoxicity

The tryptophan/kynurenine pathway (TKP) is the main route of tryptophan degradation and generates several neuroactive and immunomodulatory metabolites. Experimental and clinical data have clearly established that besides fat, muscle and liver, pancreatic islet tissue itself is a site of inflammation during obesity and type 2 diabetes. Therefore it is conceivable that pancreatic islet exposure to increased levels of cytokines may induce upregulation of islet kynurenine metabolism in a way resembling that seen in the brain in many neurodegenerative disorders. Using normal rat islets and the INS-1 β-cell line, we have demonstrated for the first time that: 1/only some TKP genes are constitutively expressed, both in β-cells as well as non β-cells; 2/ the regulatory enzyme indoleamine 2,3-dioxygenase (IDO1) is not constitutively expressed; 3/ IDO1 and kynurenine 3-monoxygenase (KMO) expression are potently activated by proinflammatory cytokines (IFN-γ, IL-1β) and glucolipotoxicity respectively, rather in β-cells than in non β-cells; 4/ Islet kynurenine/kynurenic acid production ratio is enhanced following IFN-γ and glucolipotoxicity; 5/ acute exposure to KYN potentiates glucose-induced insulin secretion by normal islets; and 6/ oxidative stress or glucocorticoid modulates TKP genes only marginally. Pancreatic islets may represent a new target tissue for inflammation and glucolipotoxicity to activate the TKP. Since inflammation is now recognized as a crucial mechanism in the development of the metabolic syndrome and more specifically at the islet level, it is needed to evaluate the potential induction of the TKP in the endocrine pancreas during obesity and/or diabetes and its relationship to the islet cell functional alterations.

Synergism between growth-factors in the control of glioma cell-proliferation, migration and invasion in-vitro

Gliomas constitute more than 50% of primary brain tumours in man. Perhaps the most important hallmark of these tumours is their diffuse invasion of the normal brain structures. The biological factors involved in the control of both their proliferation and invasion are, however, not well known. We studied the expression of receptors for epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), platelet derived growth factor (PDGF), and transforming growth factor beta-1 (TGF-beta 1) in low grade astrocytoma (IPNT-H)-, grade III astrocytoma (IPSB-18)-, and glioblastoma (IPRM-5)- derived cell lines. The effects of EGF, bFGF, PDGF, and TGF-beta 1 on proliferation, migration, and invasion in vitro were also investigated. When tested individually, EGF, bFGF and PDGF, were found to differentially stimulate proliferation, motility and invasion of the cell lines examined. When combined, these three growth factors acted synergistically to stimulate these biological properties. In addition, TGF-beta 1 exhibited positive and negative effects on the mitogenic action of the other growth factors in IPNT-H cells but inhibited their activity in IPSB-18 and IPRM-5 cells. Moreover, TGF-beta 1 was found to modulate negatively and positively the migration and invasion promoting action of the other growth factors in IPNT-H and IPSB-18 cells, while it strongly potentiated this action in IPRM-5 cells. These results suggest that all the growth factors examined may play key roles in the control of the biological properties of human glioma cells in vitro. Together with our findings that TGF-beta 1 is overexpressed in human glioblastoma in vivo, these results also suggest that co-operation between growth factors and TGF-beta 1 may be of central importance in tumour progression of gliomas.

Differential-effects of transforming growth-factor-Beta-1 on protein-levels of p21 waf and cdk-2 and on cdk-2 kinase-activity in human rd and ccl64 mink lung-cells

Currently, the cyclin-dependent kinase inhibitor p21 WAF-1 is considered to be a crucial downstream effector in the p53-specific pathway of negative growth control in mammalian cells. Wild-type p53, but not mutant forms of this protein, transactivate the WAF-1 gene. We show a correlation between growth-inhibition and induction of WAF-1 protein expression following transforming growth factor-beta 1 (TGF-beta 1) treatment of two human tumour cell lines devoid of wild-type p53 protein and in SV40-transformed WI38 fibroblasts. Inversely, TGF-beta 1 treatment of normal WI38 fibroblasts stimulates their growth and represses WAF-1 protein synthesis. As the mink lung epithelial CCL64 cell line is frequently used in TGF-B studies we included it in this study: TGF-beta 1 growth-inhibition is accompanied by induction of WAF-1 synthesis concomitantly with a reduction of cdk2 synthesis and of its histone kinase activity. However in the human tumour line RD, TGF-beta 1 did not affect cdk-2 protein levels but did reduce its histone kinase activity.

Altered complex formation between p21waf, p27kip and their partner G1 cyclins determines the stimulatory or inhibitory transforming growth factor-beta1 growth response of human fibroblasts

TGF-beta1 stimulates proliferation of WI38 human embryo fibroblasts but inhibits that of their SV40-transformed counterparts, VA13 cells. Protein expression levels of cyclins A, D1, E and that of cdk2 and cdk4 were not affected by TGF-beta1 in either of these cells. However, TGF-beta1-treatment increases cdk2 kinase activity in WI38 cells and reduces it in VA13 cells. The same treatment reduces the amount of p21waf present in complexes with cyclins D1 and E in growth-stimulated WI38 cells, but the reverse applies in growth-inhibited VA13 cells. Mitogenic stimulation of WI38 fibroblasts correlated with decreased expression of p27kip protein and reduced amounts of it in complex with cyclin E. In contrast, proliferative inhibition of VA13 fibroblasts by TGF-beta1 caused a reduction of p27kip in complexes with cyclin D1, but increased it in complexes with cyclin E, without affecting the overall level of p27kip protein expression. Thus, in this human fibroblast model, TGF-beta1-mediated stimulation or inhibition of proliferation depends on modulation in the amounts of p21waf and p27kip in complexes with cyclins D1 and E.

Growth stimulation of murine fibroblasts by TGF-beta1 depends on the expression of a functional p53 protein

Transforming Growth Factor-beta1 (TGF-beta1) inhibits the proliferation of most cells, but stimulates some mesenchymal cell types, including murine NIH3T3 fibroblasts. We show here that TGF-beta1 growth stimulation of NIH3T3 fibroblasts is reversed when these cells are transformed by SV40 or are transfected with a plasmid encoding the SV40 Large T antigen. Inversion of the TGF-beta1 growth stimulation of NIH3T3 cells is not observed when these cells are transfected with plasmids expressing either a mutant Large T, unable to bind P53, or the E1A adenovirus oncoprotein which binds the retinoblastoma protein pRB but not P53. But when the TGF-beta1-growth stimulated cells are transfected with a plasmid expressing a mutant form of Large T capable of binding to P53, but not to pRB, or with one expressing the E1B-55 kD adenovirus oncoprotein, which also binds to P53 but not to pRB, the cells are growth-inhibited by TGF-beta1. The cdk inhibitor p21Waf is decreased in TGF-beta1-stimulated NIH3T3 fibroblasts and increased in TGF-beta1-inhibited SV40-transformed cells. Finally, we show that T12 fibroblasts, from a P53 knockout mouse, are growth inhibited by TGF-beta1 and that they remain so upon transfection with a P53 which is mutant at restrictive temperature, but become growth-stimulated by this factor at permissive temperature when P53 is functional. These data strongly suggest that growth-stimulation of fibroblasts by TGF-beta1 depends on the presence of a functional P53 protein and that inversion of this response occurs if P53 is absent or inactivated.

Transforming growth factor-beta1 enhances the lethal effects of DNA-damaging agents in a human lung-cancer cell line

In tissue culture conditions, exogeneous active transforming growth factor-beta1 (TGF-beta1) enhances the lethal effect of DNA-damaging agents (UV-C, gamma rays, cisplatin, methotrexate and 5-fluorouracil) toward human A549 cells and mink Mv1Lu cells, as detected by the loss of their capacity to give rise to colonies; both these cell lines harbor a wild-type p53, as determined by immunoprecipitation. Contrastingly, the sole effect of the cytokine used alone is to inhibit reversibly the multiplication of the same cells without further impairing, once withdrawn from their environment, their capacity to divide and give rise to colonies. The lethal synergy between TGF-beta1 and UV-C was studied on mink and human cell lines, and the biomodulation by TGF-beta1 of cell killing by cisplatin, gamma rays, 5-fluorouracil or methotrexate was tested only on human cells. As investigated with UV-C-irradiated human A549 cells, TGF-beta1 appears to enhance apoptosis rather than to disturb the repair of DNA photolesions (mainly pyrimidine dimers) by the nucleotidic excision repair pathway according to results of nucleosomal ladder and comet tests. Our data raise the possibility that, in vivo, TGF-beta1 might affect the curative and/or undesirable secondary side effects of cancer therapy.

Human wild type p53 inhibits cell proliferation and elicits dramatic morphological changes in human glioma cell lines in vitro

A human pilocytic astrocytoma-derived cell line, a grade III astrocytoma-derived cell line, and a glioblastoma-derived cell line were transfected with the human wild-type p53 gene, in order to demonstrate the possible suppressor role of this gene in low grade as well as in high grade human astrocytomas. p53 exhibited a strong growth suppressor effect on the three cell lines studied, irrespective of the grade of malignancy of the tumours from which they originate. Furthermore, the p53 gene elicited important morphological changes in these cell lines. p53-Transfected cells displayed a flat morphology, a large cell body, and a stellate shape with long processes, characteristic of differentiated astrocytes. In addition, the growth inhibitory effect of p53 was found not to be due to induction of apoptosis. These results indicate that p53 plays a tumour suppressor role in low grade and high grade human astrocytomas and raise the possibility of the involvement of p53 in glioma cell differentiation in vitro.

Transforming growth factor-beta 1 enhances serum-induced dephosphorylation of the P53 protein in cell lines growth-inhibited by this factor

A 24 hr TGF-beta 1 treatment (4 ng/ml) of SV40-transformed WI38 embryonic fibroblasts (VA13 cells) causes a moderate but reproducible inhibition of their serum-stimulated growth. By immunoprecipitation with the PAb122 antibody, we show that serum stimulation of previously serum-deprived cells causes a dephosphorylation of the wild type P53 protein, which is accentuated by the TGF-beta 1 treatment. The TGF-beta 1-enhanced dephosphorylation effect is also observed in two other cell lines growth-inhibited by TGF-beta 1, but which do not contain Large T (mink lung CCL64 and human KHOS cells). On the contrary, TGF-beta 1 treatment of the untransformed WI38 fibroblasts stimulates their growth, without affecting the phosphorylation of P53. Such treatment did not affect the expression of the corresponding mRNA nor the level of synthesis of the protein. The results suggest that the P53 protein could be a downstream target of TGF-beta 1 action on those cells growth-inhibited by the factor.